Magnetic work holder



Jan. 9, 1940. s. KOLLER MAGNETIC WORK HOLDER Filed May 13, 1959 2Sheets-Sheet 1 Sieren Kalle? W QWN S. KOLLER MAGNETIC WORK HOLDER FiledMay 13, 1939 2 Sheets-Sheet 2 gwuc/wboas (q Sieve}: K lie? Patented Jan.9, 1 940 UNITED STATES PATENT OFFICE "Steven Koller, Detroit, Mich.

- Application May 13, 1939, Serial No. 273,553

Claims.

This invention relates to improvements in work holding devices andpertains particularly to an improved magnetic chuck.

The present invention has .for its primary object .to provide animproved permanent magnet chuck by means of which articles of magneticmaterial which are to be worked upomfor example,to beground, are held ina desired working position by magnetic force, the device including meanswhereby the piece of work may be released through the shifting of thepermanent magnets to a non-working position.

Another object of the invention is to provide in a permanent magnetchuck of the character specified, novel means for divertingthe flow ofmagnetic flux between the poles of the permanent magnets forming a partof the device whereby the flux wil become effective to hold a magneticbody in position on the chuck, orv for shunting the-magnetic fiux fromthe body of magnetic material so that it will flow directly between thepoles of the permanent magnets and thereby release the magnetic bodyfrom holding position.

Ihe invention will be best understood from a consideration of thefollowing detailed description taken in connection with the accompanyingdrawings forming part of this specification, with the understanding,however, that the invention is not to be confined to any strictconformity with the showing of the drawings butmay be changed ormodified so long as such changes or modifications mark no materialdeparture from the salient features of the invention as expressed in theappended claims.

Fig. 3 is a sectional view taken substantially on the line 3--3 of Fig.,2. v

-Fig. 4 isa fragmentary view illustrating the position to which a magnetunit may be oscillated from the position in which the units are shown inFig. 2. g

Fig. 5 is a sectional view on the line 5-5 of Fig. v2, showing themagnet unit in off or nonholding position with respect to a body of work7 which may be placed upon the top of the chuck.

Fig. 6 is a sectional View corresponding to Fig. 5, but showing themagnetic unit turned to on or work holding position.

Referring now more particularly to the drawings, the numeral I generallydesignates the bottom or base plate of the present permanent magnetchuck, which plate may be secured in any desired manner to a suitablesupporting base. 5

Disposedover and resting upon the base I is a box unit 2 which has theupstanding side and end walls 3 and 4, respectively, and the integraltop wall '5- in which is formed anopening- 6 which extendslongitudinally of the top wall and 10 through the ends thereof, thesides of this opening 6 being downwardly divergent so that the openingin cross-section is of dove-tail form.

Designed to be fitted into the opening 6 is a unit indicated generallyby the numeral 1 and -made up of longitudinally extending strips of softiron 8 and non-magnetic material 9, such as brass or the like arrangedalternately as shown in Figs. 5 and 6. These strips which make up theunit 'I are secured together by the transversely extending pins ll) ofbrass or other non-magnetic material and this unit, which in effectconstitutes the work supporting head or work holding head, is positionedin the opening 6 by being inserted-longitudinally from one end acrossthe top edge of an end wall 4, as illustrated in Fig. 3.

After the head unit I is located in position, it is secured againstlongitudinal movement by the attachment of end cover plates H which aresecured by screws l2 or in any other suitable manner to the end walls 4.

The box 2 is secured to the base plate I by suitable vertical securingpins or bolts l3 which, as shown in Figs. 2 and 3, pass upwardly throughthe base into the walls of the box. I

Within the chamber C which is formed by the box or casing 2; there isarranged a series or group of permanent magnet units, each of whichunits is indicated by the numeral 14. Each of these units is' made up ofa plurality of horseshoe mag- 40 nets 15 which are secured together inside by side relation, as shown by bolts I6 of non-magnetic materialwhich pass through the magnets between the legs thereof. These boltsalso pass through the vertically arranged side plate ll of an anglebracket of' non-magnetic material, the other plate of which is indicatedby the numeral l8 and is horizontally arranged, passing beneath themagnets l5, as shown in Fig. 5.

The bottom plate l8 of each magnet unit supporting bracket has securedto it a pivot pin or stud J9, which extends ,downwardly through abearing unit 20 which'is disposed in a suitable opening 2| within thebase plate I, the stud I9 beingheld against removal from the bearing s5unit by a screw and washer assembly 22, as'

shown in Figs. 5 and 6. By this arrangement each magnet unit issupported for oscillation on a vertical axis. The ends of the legs ofthe magnets are directed upwardly and are disposed in close proximity tothe underside of the workholding head unit I.

The numeral 23 designates an actuating plate by means of which thesimultaneous oscillation of the magnet units I4 is effected. This plateis disposed upon the top of the base I for sliding or shifting movementtransversely thereof, beneath the plates l8 of the magnet unitsupporting brackets and it is provided with the series or group oflongitudinally extending slots 24, each of which receives a coupling pin25 which is carried by the adjacent bracket plate l8 and which extendsdownwardly therefrom adjacent a corner of the magnet unit. As shown inFig. 2, the coupling pin receiving slots are so arranged that when theplate 23 is in one position or is adjacent one side of the chamber C,all of the magnet units within the chamber will be arranged so that thepath of magnetic flux between the poles of the magnets of each unit willflow longitudinally of the work holding unit 1, thereby following thesoft iron strips 8 of this unit. When the plate 23 is shifted across thechamber C, it will effect the oscillation of the magnet units through aquarter turn so as to bring each of these units into the positionillustrated in Fig. 4, and also in Fig. 6, which position is at rightangles to the position of these units as they are shown in Figs. 2 and3. When in this position, it will be apparent that the path of magneticflux cannot flow between the poles of the magnets of the units becausesuch path will be at right angles to the length of the soft iron strips8 which have interosed between them the non-magnetic material 9.

The oscillation of the plate 23 is effected by the provision of a boss25' on the top of the plate at substantially its transversecenter, towhich is attached one end of a shift 26 which passes through a suitablecollar 21 mounted in the adjacent wall of the box 2, the rod terminatingin the knob 28.

It is believed that it will be readily apparent from the foregoing thatwhen a body of work W, consisting of a magnetic material, is placed uponthe work receiving head and the magnet units are arranged as shown inFig. 6, so that the path of magnetic flux betweenv the legs of themagnets through the soft iron strips 8 is interrupted, this path will beextended upwardly as indicated by the arrows in Fig. 6 to include themagnetic. body W, and in this manner the body will be firmly retainedupon the work holding head. When the body W is to be released, themagnet actuating plate 23 is shifted horizontally across the chamber Csoas to turn the magnet units to the position in which they are shown inFigs. 2, 3 and 5. The path of magnetic flux between the poles of themagnets will then'pass into and longitudinally through the soft ironstrips 8 so that it will be deliverted away from or shunted from themagnetic body W and the body will be released for removal.

In the construction of the magnetic chuck described, it is preferredthat use be made of the horseshoe type of permanent magnet as magnets ofthis character are made which are capable of lifting approximately fortytimes their own weight whereas the use of the old-fashioned straightmagnets is undesirable because they have the ability only of liftingapproximately four times their own weight.

By the grouping of such horseshoe magnets in the manner shown and by thearrangement of such groups or units in a series, as illustrated, it willbe readily apparent that a particularly powerful holding action may beobtained upon a body of magnetic material placed upon' the disposedbeneath said head with the ends of the side portions thereof directedtoward the head. and supporting means facilitating the oscilla tion ofsaid magnet on an axis perpendicular to the head whereby said magnet maybe turned to either of two positions with respect to the head to causethe magnetic flux between the poles of the magnet to pass longitudinallythrough said magnetic strips or to divert said flow upwardly through themagnetic strips and between the non-magnetic strips to pass through themagnetic body upon the head.

2. A magnetic work holder, comprising a chambered body having a topplate provided with an opening, a magnetic material supporting headsecured in said opening and consisting of a series of alternatelyarranged parallel strips of magnetic and non-magnetic material, aplurality of magnetic units within the chamber eachunit consisting of agroup of horseshoe magnets\secured in side by side relation and havingtheir poles directed toward the underside of said head and in closeproximity thereto, a supporting bracket for each group of magnets, andmeans operable from outside said chamber for turning said supportingbrackets and the group of magnets carried thereby through asubstantially 90 path whereby said magnet groups may be shifted from aposition where all are arranged to permit the path of magnetic fluxbetween their poles to extend longitudinally along the said magneticstrips or to a position where said path will be at right angles to saidstrips.

3. A magnetic work holder, comprising a body forming a base, a secondbody forming a casing supported upon the base, the casing including ahorizontal top wall having an opemng therein, a work supporting headsecured in said opening and consisting of alternately arrangedstrips ofmagnetic and non-magnetic material. a plurality of magnet units disposedwithin the casing beneath said head and each consisting of a group ofhorseshoe magnets arranged in side by side relation with their polesdirected toward, the underside of the head and in close'proximitythereto, a bracket supporting each group of magnets, a pivot pin carriedby each bracket and extending downwardly into said base whereby eachgroup of magnets may be oscillated on an axis extending perpendicular tothe head, and means common t simultaneous oscilla ion of the samethrough a 90 arc whereby said units may be arranged to cause the pathsof magnetic'flux between the poles of the magnets to extendlongitudinally of the strips or to extend transversely thereof.

4. A magnetic work holder, comprising a head unit designed to support abody of work of magsaid brackets for efiecting flux longitudinally neticmaterialand having inner and outer plane s between the magnetic stripsand through the magnetic piece of work and when in another positionrelative to the head unit releasing the piece of work through passage-ofthe magnetic of the magnetic strips from one pole to the other pole, andmeans for oscillating one unit relative to the other on an axisperpendicular to the work supporting plane surface of the head unit.

5. A magnetic work holder, comprising a work supporting head havinginner and outer plane surfaces, said head consisting of alternatelyarranged strips of magnetic and non-magnetic material, a permanentmagnet supported beneath said head for turning on a vertical axis, saidmagnet having poles disposed in a plane spaced from but adjacent to theinner plane surface of the head, and means for turning said magnet toeither of two positions, in one of whichvpositions the magnetic fluxpath between the poles will pass vertically through and transverselybetween said magnetic strips through work on the head to hold the workthereon and in the other position the flux will pass longitudinally ofthe v magnetic strips to shunt the flux out of the work to release itfrom the head. STEVEN KOLLER.

